Long-chain polyunsaturated fatty acids in plasma lipids of obese children

Fatty acid composition of plasma phospholipids (PL), triglycerides (TG), and sterol esters (STE) was determined by high-resolution capillary gas-liquid chromatography in 22 obese children (age: 13.7±1.4 y, body weight relative to normal weight for height: 170±24%, mean ±SD) and compared with data obtained in 25 age-matched healthy controls. There were no differences in the levels of linoleic acid (LA, C_18∶2n-6) in any of the plasma fractions from the obese children and the controls. Obese children exhibited significantly higher values of arachidonic acid (AA, C_20∶4n-6) than controls both in PL (12.6 [2.4] vs. 8.3 [1.4], % wt/wt, [median (interquartile range)],P<0.001) and STE (7.3 [1.8] vs. 6.0 [1.1],P<0.05). Similarly, obese children showed higher values than controls for dihomo-γ-linolenic acid (DHGLA, C_20∶3n-6) in PL (4.0 [0.5] vs. 3.0 [0.6],P<0.001), TG (0.4 [0.1] vs. 0.2 [0.1],P<0.001), and STE (0.9 [0.1] vs. 0.7 [0.1],P<0.01), and for γ-linolenic acid (C_18∶3n-6) in STE (1.1 [0.2] vs. 0.8 [0.2],P<0.001). The AA/LA ratios were higher in obese children than in controls in PL (0.68 [0.16] vs. 0.42 [0.09],P<0.0005) and STE (0.16 [0.04] vs. 0.12 [0.02],P<0.05), whereas the AA/DHGLA ratios were lower in TG of obese children than in controls (3.40 [0.64] vs. 5.10 [1.75],P<0.005). Plasma glucose concentrations were inversely related to AA in TG (r=0.53,P<0.05), and plasma TG concentrations were inversely related to AA in PL and STE (r=−0.49,P<0.05 andr=−0.48,P<0.05) and to the AA/DHGLA ratios in PL (r=−0.57,P<0.01),TG (r=−0.56,P<0.01) and STE (r=−0.56,P<0.01). We conclude that the significantly higher values of n-6 long-chain polyunsaturated fatty acids (LCP) in plasma lipids of obese children than in age-matched controls may be caused by an enhanced activity of Δ6-desaturation, and we speculate that elevated fasting immunoreactive insulin seen in obese children (19.4±8.0 μU/mL) may stimulate synthesis of n-6 LCP fatty acids.     

n-3 Polyunsaturated Fatty Acids and Atopy in Korean Preschoolers

Atopy is a growing problem for Korean children. Since eicosapentaenoic acid is a precursor of less active inflammatory eicosanoids, n-3 polyunsaturated fatty acids (PUFA) may have a protective effect on atopy. This study was undertaken to determine whether n-3 PUFA in red blood cells (RBC) is lower in atopic than in non-atopic preschoolers. Three hundred and eight Korean children aged 4–6 years were enrolled. Total RBC fatty acid composition was measured by gas chromatography. The prevalence of atopic dermatitis, allergic rhinitis, or asthma was 29%. Total RBC n-3 PUFA were lower in preschoolers with atopy than controls (9.8 ± 1.2 vs. 11.4 ± 1.6%; P < 0.05), while n-6 PUFA (33.0 ± 1.4 vs. 32.2 ± 1.0%; P < 0.05) and n-6/n-3 PUFA ratio (3.4 ± 0.6 vs. 2.8 ± 0.5; P < 0.05) were greater. The following factors were also associated with an increase in atopy: higher saturated fatty acids (39.6 ± 1.4 vs. 40.6 ± 1.9; P < 0.05) and arachidonic acid (15.3 ± 1.6 vs. 16.0 ± 2.9; P < 0.05), and lower total PUFA (43.8 ± 0.7 vs. 42.8 ± 1.4; P < 0.05) and omega-3 index (EPA + DHA; 9.1 ± 0.8 vs. 7.8 ± 0.5; P < 0.05) in RBC. Maternal history of atopy was a significant (P < 0.05) risk factor, while lactation was not. The results suggest that a reduced content of n-3 PUFA in the RBC membrane could play a role in early children atopy.     

Evaluation of a Rapid Assessment Questionnaire Using a Biomarker for Dietary Intake of n-3 Fatty Acids

While there is considerable evidence supporting health benefits of consuming diets high in omega-3 (n-3) fatty acids, there is no quick and effective tool to measure n-3 intake. The objective of this study was to evaluate the accuracy of a rapid assessment questionnaire (the Omega-3 Checklist) used to quantify intake of n-3 fatty acids. This was done by comparing n-3 intakes to blood biomarkers of n-3 exposure in a population of healthy men and women. In addition, a separate analysis was run including covariates age, sex, and weight, which have been shown to affect n-3 biomarker levels. Reported intake of eicosapentaenoic acid (EPA), docoshexaenoic acid (DHA), and EPA + DHA was correlated with erythrocyte EPA (Spearman’s rank correlation r_s = 0.51, p < 0.001), DHA (r_s = 0.54, p < 0.001), and the Omega-3 Index (r_s = 0.57, p < 0.001). These associations remained significant when controlling for age, sex, and weight. Therefore, the Omega-3 Checklist can be a useful, rapid assessment tool to estimate individuals’ EPA and DHA intake.     

Consumption of Dietary n-3 Fatty Acids Decreases Fat Deposition and Adipocyte Size, but Increases Oxidative Susceptibility in Broiler Chickens

The aim of this study was to determine the effects of an omega-3 (n-3) polyunsaturated fatty acid (PUFA)-enriched diet on animal fat depots and lipid oxidation in the blood and meat of broiler chickens. Abdominal fat pad (AFP), sartorius muscle and liver histology were used to assess the effect of the dietary fat on animal lipid depots. A total of 60 female broilers (14 days old) was randomly divided into two groups which received a diet containing 10 % of tallow (S diet), rich in saturated fatty acids or 10 % of a blend of fish oil and linseed oil (N3 diet), rich in n-3 PUFA from 14 to 50 days of life. Both absolute and relative weights of AFP in N3 animals were lower than in the S group (P < 0.05). These results paralleled with a lower adipocyte mean area (P < 0.001) obtained in N3-fed animals, leading to a higher number of fat cells per unit of surface measured (383.4 adipocytes/mm² vs. 273.7 adipocytes/mm²). Similarly, fat content and the intramuscular fat-occupied area of muscle were lower in N3 (P < 0.0001) than in the S-fed birds. Neither macroscopic nor microscopic differences were observed in the liver. The inclusion of dietary n-3 PUFA increased meat and erythrocyte oxidation susceptibility; however, the erythrocytes from the S group were less resistant to osmotic changes. Results indicate that feeding an n-3 PUFA diet influences fat distribution and the oxidative status of broiler chickens.     

Phosphorus Fractionation and Sorption in P-enriched Soils of Norway

Phosphorus (P) enrichment can lead to imbalance in nutrient availability and pollution of terrestrial and aquatic ecosystems. Hence studies were carried out to investigate fractionation and sorption of P in eleven P-enriched soils collected from different agro-climatic sites in Norway. Different P fractions viz. total, organic, inorganic (easily soluble P, Fe-P, Al-P, Ca-P and occluded P), P_w (water extractable), and NH₄-lactate extractable P (P_AL) at the beginning and after the completion of the experiments varied widely among the soils studied, indicating a wide variability of P supplying capacity of these soils. Soluble P was positively correlated to Ca-P (r = 0.94; P < 0.001), P_w (r = 0.87; P < 0.001), pH (r = 0.79; P < 0.01) and P_AL (r = 0.79; P < 0.01), whereas it was negatively correlated with ammonium oxalate-extractable Al (Al_ox) (r = ?0.68; P < 0.05). Iron-P was only moderately related to Al_ox(r = 0.64; P < 0.05) and P_ox(r = 0.70; P < 0.05), whereas it was not related to any of the other parameters tested. The α [α = P_ox/(Fe_ox + Al_ox)] was highly correlated with P_AL (r = 0.93; P < 0.001), pH (r = 0.87; P < 0.001), inorganic P (r = 0.80; P < 0.01) and P_w(r = 0.77; P < 0.01) but moderately to total P (r = 0.71; P < 0.05). Adsorption data fitted well to the Langmuir equation for most soils. The P affinity constant (k), adsorption maximum (b) and thus maximum buffering capacity (mbc) and adsorption isotherm of P were highest in the sandy clay soil from Øsaker, which also contained high amounts of Fe, Al and clay particles and the lowest in sandy soil from Vestrålen, which contained very high initial P_ALand the lowest content of Fe, Al, silt and clay among all the soils studied. The P affinity constant (k) was correlated positively and significantly to clay content (r = 0.66; P < 0.05), whereas mbc was correlated positively and significantly to clay content (r = 0.63; P < 0.05) and ammonium oxalate-extractable Fe (Fe_ox) (r = 0.63; P < 0.05). Phosphorus desorption of the soils varied widely depending on the initial P status and texture of the soils. Phosphorus desorbed by NH₄-lactate was many fold higher as compared to CaCl₂ in most soils.     

Trans isomeric octadecenoic acids are related inversely to arachidonic acid and DHA and positively related to mead acid in umbilical vessel wall lipids

Long-chain PUFA play an important role in early human neurodevelopment. Significant inverse correlations were reported between values of trans isomeric and long-chain PUFA in plasma lipids of preterm infants and children aged 1–15 yr as well as in venous cord blood lipids of full-term infants. Here we report FA compositional data of cord blood vessel wall lipids in 308 healthy, full-term infants (gestational age: 39.7±1.2 wk, birth weight: 3528±429 g, mean±SD). The median (interquartile range) of the sum of 18-carbon trans FA was 0.22 (0.13)% w/w in umbilical artery and 0.16 (0.10)% w/w in umbilical vein lipids. Nonparametric correlation analysis showed significant inverse correlations between the sum of 18-carbon trans FA and both arachidonic acid and DHA in artery (r=−0.38, P<0.01, and r=−0.20, P<0.01) and vein (r=−0.36, P<0.01, and −0.17, P<0.01) wall lipids. In addition, the sum of 18-carbon trans FA was significantly positively correlated to Mead acid, a general indicator of EFA deficiency, in both artery (r=+0.35, P<0.01) and vein (r=+0.31, P<0.01) wall lipids. The present results obtained in a large group of full-term infants suggest that maternal trans FA intake is inversely associated with long-chain PUFA status of the infant at birth.     

Comparative Effects of Sandalwood Seed Oil on Fatty Acid Profiles and Inflammatory Factors in Rats

The aim of the present study was to investigate the effect of sandalwood seed oil on fatty acid (FA) profiles and inflammatory factors in rats. Fifty male Sprague–Dawley rats were randomly divided into five different dietary groups: 10 % soybean oil (SO), 10 % olive oil (OO), 10 % safflower oil (SFO), 10 % linseed oil (LSO) and 8 % sandalwood seed oil blended with 2 % SO (SWSO) for 8 weeks. The SWSO group had a higher total n-3 polyunsaturated fatty acids (PUFA) levels but lower n-6:n-3 PUFA ratios in both adipose tissue and liver than those in the SO, OO and SFO groups (p < 0.05). Although the SWSO group had a much lower 18:3n-3 level (4.51 %) in their dietary lipids than the LSO group (58.88 %), the levels of docosahexaenoic acid (DHA: 22:6n-3) in liver lipids and phospholipids of the SWSO group (7.52 and 11.77 %) were comparable to those of the LSO group (7.07 and 13.16 %). Ximenynic acid, a predominant acetylenic FA in sandalwood seed oil, was found to be highly incorporated into adipose tissue (13.73 %), but relatively lower in liver (0.51 %) in the SWSO group. The levels of prostaglandin F_2α, prostaglandin E₂, thromboxane B₂, leukotriene B₄, tumor necrosis factor-α and interleukin-1β in both liver and plasma were positively correlated with the n-6:n-3 ratios, suggesting that increased n-6 PUFA appear to increase the formation of pro-inflammatory cytokines, whereas n-3 PUFA exhibit anti-inflammatory activity. The present results suggest that sandalwood seed oil could increase tissue levels of n-3 PUFA, DHA and reduce the n-6:n-3 ratio, and may increase the anti-inflammatory activity in rats.     

Dietary Docosahexaenoic Acid and <Emphasis Type="Italic">trans</Emphasis>-10, <Emphasis Type="Italic">cis</Emphasis>-12-Conjugated Linoleic Acid Differentially Alter Oxylipin Profiles in Mouse Periuterine Adipose Tissue

Diets containing high n-3 polyunsaturated fatty acids (PUFA) decrease inflammation and the incidence of chronic diseases including cardiovascular disease and nonalcoholic fatty liver disease while trans-fatty acids (TFA) intake increases the incidence of these conditions. Some health benefits of n-3 PUFA are mediated through the impact of their oxygenated metabolites, i.e. oxylipins. The TFA, trans-10, cis-12-conjugated linoleic acid (CLA; 18:2n-6) is associated with adipose tissue (AT) inflammation, oxidative stress, and wasting. We examined the impact of a 4-week feeding of 0, 0.5, and 1.5% docosahexaenoic acid (DHA; 22:6n-3) in the presence and absence of 0.5% CLA on AT oxylipin profiles in female C57BL/6N mice. Esterified oxylipins in AT derived from linoleic acid (LNA), alpha-linolenic acid (ALA), arachidonic acid (ARA), eicosapentaenoic acid (EPA), DHA, and putative from CLA were quantified. CLA containing diets reduced AT mass by ~62%. Compared with the control diet, the DHA diet elevated concentrations of EPA-and DHA-derived alcohols and epoxides and LNA-derived alcohols, reduced ARA-derived alcohols, ketones, epoxides, and 6-keto-prostaglandin (PG) F_1α (P < 0.05), and had mixed effects on ALA-derived alcohols. Dietary CLA lowered EPA-, DHA-, and ALA-derived epoxides, ARA-derived ketones and epoxides, and ALA-derived alcohols. While dietary CLA induced variable effects in EPA-, DHA-, and LNA-derived alcohols and LNA-derived ketones, it elevated ARA-derived alcohols and PGF_1α, PGF_2α, and F2-isoprostanes. DHA counteracted CLA-induced effects in 67, 57, 43, and 29% of total DHA-, ARA-, EPA-, and ALA-derived oxylipins, respectively. Thus, CLA elevated proinflammatory oxylipins while DHA increased anti-inflammatory oxylipins and diminished concentration of CLA-induced pro-inflammatory oxylipins in AT.     

Effect of ALA-Enriched Food Supply on Cardiovascular Risk Factors in Males

The outcome of a total dietary approach using a wide range of n-3 polyunsaturated fatty acids (PUFA) enriched food items on cardiovascular diseases called for further investigation. The study objective was to assess the effect of an ALA-enriched food supply on cardiovascular risk factors in healthy males. A dietary intervention (single-blind field trial with pre- and post-measurements) was performed with 59 healthy males in a Belgian prison. Over a period of 12 weeks they were supplied with an n-3 enriched diet (containing 6.5 g n-3 PUFA/day compared to 4 g n-3 PUFA/day in the standard diet) that was substituted for their regular diet, increasing mainly the α-linolenic acid intake (from 2.8 to around 5 g/day). The results indicated no impact on subjects waist circumference, weight and BMI or systolic blood pressure. In contrast, the diastolic blood pressure significantly decreased during the intervention period (from 74.6 ± 8.2 to 71.7 ± 10.1 mmHg; P < 0.02). Moreover, the HDL-cholesterol level increased in non-smoking participants (from 0.97 ± 0.25 to 1.06 ± 0.23 mmol/l; P < 0.03). In summary, the study demonstrated that enrichment of commonly eaten food items with n-3 fatty acids provides the opportunity to increase the n-3 fatty acid intake and to decrease the n-6/n-3 ratio which results in a decreasing diastolic blood pressure and an increase of HDL-cholesterol (in non-smokers). An erratum to this article can be found at     

The fatty acid composition of human gliomas differs from that found in nonmalignant brain tissue

To compare the fatty acid composition of tumor tissue from glioma patients with that of normal brain tissue, tissue samples were obtained from 13 glioma patients and from 3 nonmalignant patients. Following lipid extraction, total fatty acid composition was measured using gas-liquid chromatography. Samples were further separated into phospholipids and neutral lipids. Representative samples were then separated into phospholipid classes by thin-layer chromatography and the fatty acid composition assayed. Levels of the polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA), were significantly reduced (P=0.029) in the glioma samples compared with normal brain samples; mean values were 4.8±2.9% and 9.2±1.0%, respectively. This reduction in glioma DHA content was also observed in terms of phospholipids (4.6±2.1% vs. 9.6±0.8%,P=0.002). The phosphatidylserine and phosphatidylethanolamine phospholipid classes were reduced in the glioma samples. Differences were also noted in the n-6 PUFA content between glioma and normal brain samples. The glioma content of the n-6 PUFA linoleic acid was significantly greater (P<0.05) than that observed in the control samples in terms of total lipids. Thus, the fatty acid composition of human gliomas differs from that found in nonmalignant brain tissue.     

Limited Effect of Dietary Saturated Fat on Plasma Saturated Fat in the Context of a Low Carbohydrate Diet

We recently showed that a hypocaloric carbohydrate restricted diet (CRD) had two striking effects: (1) a reduction in plasma saturated fatty acids (SFA) despite higher intake than a low fat diet, and (2) a decrease in inflammation despite a significant increase in arachidonic acid (ARA). Here we extend these findings in 8 weight stable men who were fed two 6-week CRD (12%en carbohydrate) varying in quality of fat. One CRD emphasized SFA (CRD-SFA, 86 g/d SFA) and the other, unsaturated fat (CRD-UFA, 47 g SFA/d). All foods were provided to subjects. Both CRD decreased serum triacylglycerol (TAG) and insulin, and increased LDL-C particle size. The CRD-UFA significantly decreased plasma TAG SFA (27.48 ± 2.89 mol%) compared to baseline (31.06 ± 4.26 mol%). Plasma TAG SFA, however, remained unchanged in the CRD-SFA (33.14 ± 3.49 mol%) despite a doubling in SFA intake. Both CRD significantly reduced plasma palmitoleic acid (16:1n-7) indicating decreased de novo lipogenesis. CRD-SFA significantly increased plasma phospholipid ARA content, while CRD-UFA significantly increased EPA and DHA. Urine 8-iso PGF_2α, a free radical-catalyzed product of ARA, was significantly lower than baseline following CRD-UFA (?32%). There was a significant inverse correlation between changes in urine 8-iso PGF_2α and PL ARA on both CRD (r = ?0.82 CRD-SFA; r = ?0.62 CRD-UFA). These findings are consistent with the concept that dietary saturated fat is efficiently metabolized in the presence of low carbohydrate, and that a CRD results in better preservation of plasma ARA.     

A new relationship between total/high density lipoprotein cholesterol and polyunsaturated fatty acids

Dietary and plasma fatty acids have been linked to total cholesterol but not to the ratio of total/high-density lipoprotein cholesterol (TC/HDLC). To evaluate the relationship between dietary and plasma levels of polyunsaturated fatty acids (PUFA) and TC/HDLC, we analyzed cross-sectional and longitudinal data using 519 plasma samples (50% men, 50% women) from subjects participating in the Framingham Heart Study and results from a study feeding diets rich in either n-6 linoleic acid or n-3 α-linolenic acid with or without fish oil supplements (n-3 derivatives). Values of TC/HDLC are inversely related to the percent of plasma PUFA when both variables are measured at the same time in different subjects,R=0.82,P<0.000001. PUFA in phospholipids increase in response to increased dietary intake of different PUFA, either n-3 or n-6 or fish oils. There was a highly significant inverse relationship between TC/HDLC and the percent of PUFA in phospholipids,R=0.97,P<0.001. The relationship was similar regardless of the source and type of dietary fatty acids. A similar relationship existed when only the baseline points were considered. When plasma PUFA % increases, either in response to a diet high in PUFA or across different subjects, TC/HDLC ratios decline. Evaluation of plasma fatty acid profiles and increased balanced dietary intake of PUFA to bring fatty acid profiles of subjects with low PUFA plasma levels closer to the profile of a healthy reference group is an effective approach to reduce high TC/HDLC. Reductions of more than 50% in TC/HDLC appear feasible with dietary modification alone. Further research into fatty acid metabolic activity may determine the biochemical basis of common dysplipidemias.     

Dietary intake of professional Australian football athletes surrounding body composition assessment

Background

Sports Dietitians aim to assist in improving performance by developing nutrition knowledge (NK), enhancing dietary intake and optimising body composition of athletes. In a high-pressure environment, it is important to identify factors that may compromise an athlete’s nutrition status. Body composition assessments are regularly undertaken in sport to provide feedback on training adaptions; however, no research has explored the impact of these assessments on the dietary intake of professional athletes.

Methods

This cross-sectional study assessed dietary intake (7-day food diary), nutrition knowledge (Nutrition for Sport Knowledge Questionnaire) and body composition (Dual-energy X-ray absorptiometry) of 46 professional male Australian football (AFL) athletes during a 2017 pre-season training week (7 days) where body composition assessments were undertaken. Dietary intake was assessed against International Olympic Committee recommendations for professional athletes.

Results

Overall, no athlete met dietary their recommended energy intake (15?±?1.1 vs. 9.1?±?1.8 MJ, respectively) or carbohydrate recommendations (6–10 vs. 2.4?±?0.9 g·kg-1·day-1). Only 54% met protein recommendations. Secondary analyses demonstrated significant associations between education status and energy intake (P <?0.04) and vegetable intake (P <?0.03), with higher levels of education being associated with higher intakes. A moderately positive association was observed between NK scores and meeting estimated energy requirements (r =?0.33, P =?0.03). NK scores were also positively associated with protein (r =?0.35, P =?0.02), fibre (r =?0.51, P =?0.001) and calcium intakes (r =?0.43, P =?0.004).

Conclusions

This research identified that the dietary intake of professional AFL athletes during a pre-season training week where body composition assessments were undertaken did not meet current recommendations. Several factors may influence the dietary intake of AFL athletes, including lower education levels, poor NK and dietary intake restriction surrounding body composition assessment. Athletes may require support to continue with performance-based nutrition plans in periods surrounding body composition assessment.

     

Increased Prostaglandin Response to Oxytocin in Ewes Fed a Diet High in Omega-6 Polyunsaturated Fatty Acids

Diets high in omega-6 polyunsaturated fatty acids (n-6) are associated with increased prostaglandin F_2α (PGF_2α) synthesis in cattle, however, the specific effects on the potential prostaglandin response to an oxytocin challenge in sheep have not been reported. The aim of the current study was to determine whether oxytocin-stimulated PGF_2α was significantly increased when ewes were fed a diet high in n-6 compared with a control diet low in n-6. Merino x Border Leicester ewes (n = 30) received one of two dietary treatments, either high in n-6 (70 % oat grain) or low in n-6 (control diet, 100 % cereal/legume silage). Ewes consumed the diets for 44 days prior to two consecutive oxytocin challenges. Plasma n-6 and PGF_2α metabolite (PGFM) concentrations following oxytocin challenge were greater (P < 0.05) when ewes were fed a diet high in n-6 compared with the control diet. A higher availability of n-6 may have lead to an increased in vivo synthesis of PGF_2α, however, further research is required to determine the exact mechanisms involved.     

Effects of a Westernized Diet on the Reflexes and Physical Maturation of Male Rat Offspring During the Perinatal Period

This study evaluates the effects of a westernized diet during the perinatal period on the maternal performance and growth and development of rat offspring. Female Wistar rats were fed with either a control (C) diet, with casein as the protein source or a westernized (W) diet, during pregnancy and lactation. The pups were divided, eight per group, into the same diet groups as their dams. During lactation, the body weight (day 1, W = 6.85 ± 0.62 g, C = 5.81 ± 0.49, p < 0.05; day 21, W = 55.42 ± 3.78, C = 47.75 ± 3.45, p < 0.001) and somatic growth (body length day 1, W = 53.24 ± 2.16, C = 50.641 ± 1.79, p < 0.05; day 21, W = 124.8, C = 119.903 ± 3.71, p < 0.001) in the male offspring showed significant differences among the groups. The physical appearance and reflex maturation showed differences between day 1 and day 3. With the westernized diet, during the perinatal period, no alterations in maternal weight gain, gestation or performance were observed; however, changes in the coefficients of feed efficiency and energy during lactation were noted. Besides, blood glucose was found to be elevated at the end of lactation (C = 3.67 ± 0.35 mmol/l, W = 5.2 0 ± 0.49 mmol/l). At 21 days, the male pups from the dams on the westernized diet were 15 % heavier, and the maturation of the neural reflexes and physical characteristics were found to occur earlier. Therefore, the consumption of a westernized diet during the perinatal period was independent of maternal energy intake, and influenced the growth and development of offspring.     

The Consumption of Food Products from Linseed-Fed Animals Maintains Erythrocyte Omega-3 Fatty Acids in Obese Humans

Based on mechanistic and epidemiological data, we raise the question of the relationship between qualitative dietary polyunsaturated fatty acids (PUFA) changes and increase in obesity. In this double-blind trial, we studied the effects on 160 overweight volunteers (body mass index, BMI >30) of a 90 days experimental diet rich principally in animal fat with a low PUFA/saturated fatty acid (SFA) ratio but a low n-6/n-3 ratio, using animal products obtained from linseed-fed animals. The control diet provided less animal fat, a higher PUFA/SFA ratio and a higher n-6/n-3 ratio. Both diets excluded seafood. In the experimental group, we observed a significant increase in red blood cell (RBC) α-linolenic acid content and a slight increase in EPA and DHA derivatives, while in the control group we observed a significant reduction in EPA and DHA content. Between groups now, the difference in the three n-3 fatty acids changes in RBC was significant. This demonstrates that plasma EPA and DHA levels can be maintained without fish if products from linseed-fed animals are used. During the diets, we noted a significant reduction in weight, BMI and hip circumference within both groups of volunteers. However, no significant difference was observed between the control group and the experimental group. Interestingly, 150 days after the end of the trial (i.e., day 240), we noted a significant weight gain in the control group, whereas no significant weight gain was observed in the experimental group. This was also observed for the BMI and hip circumference. Moreover, significant differences in BMI (P < 0.05) and weight (P = 0.05) appeared between the two groups, showing in both cases a smaller increase in the experimental group. During the 90 days trial, we did not observe any differences between groups in terms of total cholesterol, HDL cholesterol, LDL cholesterol or triglycerides, suggesting that the saturate content and the P/S ratio are not as important as the n-6 and n-3 fatty acid composition.     

Relationships between the fatty acid composition of muscle and erythrocyte membrane phospholipid in young children and the effect of type of infant feeding

Muscle membrane fatty acid (FA) composition is linked to insulin action. The aims of this study were to compare the FA composition of muscle and erythrocyte membrane phospholipid in young children; to investigate the effect of diet on these lipid compositions; and to investigate differential incorporation of FA into muscle, erythrocyte and adipose tissue membrane phospholipid, and adipose tissue triglyceride. Skeletal muscle biopsies and fasting blood samples were taken from 61 normally nourished children (15 males and 16 females), less than 2 yr old (means ±SE, 0.80±0.06 yr), undergoing elective surgery. Adipose tissue samples were taken from 15 children. There were significant positive correlations between muscle and erythrocyte docosahexaenoic acid (DHA) (r=0.44, P<0.0001), total n−3 polyunsaturated fatty acids (PUFA) (r=0.39, P=0.002), and the n−6/n−3 PUFA ratio (r=0.39, P=0.002). Adipose tissue triglyceride had lower levels of long-chain PUFA, especially DHA, than muscle and erythrocytes (0.46±0.18% vs. 2.44±0.26% and 3.17±0.27%). Breast-fed infants had higher levels of DHA than an age-matched group of formulafed infants in both muscle (3.91±0.21% vs. 1.94±0.18%) and erythrocytes (3.81±0.10% vs. 2.65±0.23%). The results of this study show that (i) erythrocyte FA composition is a reasonable index of muscle DHA, total n−3 PUFA, and the n−6/n−3 PUFA ratio; (ii) breast feeding has a potent effect on the FA composition of all these tissues; and (iii) there is a wide range in long-chain PUFA levels in muscle, erythrocytes, and adipose tissue.     

Peripheral Artery Disease Is Associated with a Deficiency of Erythrocyte Membrane n-3 Polyunsaturated Fatty Acids

Population-based data suggest that individuals who consume large dietary amounts of n-3 polyunsaturated fatty acids (PUFA) have lower odds of peripheral artery disease (PAD); however, clinical studies examining n-3 PUFA levels in patients with PAD are sparse. The objective of this study is to compare erythrocyte membrane fatty acid (FA) content between patients with PAD and controls. We conducted a cross-sectional study of 179 vascular surgery outpatients (controls, 34; PAD, 145). A blood sample was drawn and the erythrocyte FA content was assayed using capillary gas chromatography. We calculated the ratio of the n-3 PUFA eicosapentaenoic acid (EPA) to the n-6 PUFA arachidonic acid (ARA) as well as the omega-3 index (O3I), a measure of erythrocyte content of the n-3 PUFA, EPA, and docosahexaenoic acid (DHA), expressed as a percentage of total erythrocyte FA. Compared with controls, patients with PAD smoked more and were more likely to have hypertension and hyperlipidemia (p < 0.05). Patients with PAD had a lower mean O3I (5.0 ± 1.7% vs 6.0 ± 1.6%, p < 0.001) and EPA:ARA ratio (0.04 ± 0.02 vs 0.05 ± 0.05, p < 0.001), but greater mean total saturated fats (39.5 ± 2.5% vs 38.5 ± 2.6%, p = 0.01). After adjusting for several patient characteristics, comorbidities, and medications, an absolute decrease of 1% in the O3I was associated with 39% greater odds of PAD (odds ratio [OR] 1.39, 95% confidence interval [CI] 1.03–1.86, and p = 0.03). PAD was associated with a deficiency of erythrocyte n-3 PUFA, a lower EPA:ARA ratio, and greater mean total saturated fats. These alterations in FA content may be involved in the pathogenesis or development of poor outcomes in PAD.     

Lipid content and fatty acid composition of 11 species of Queensiand (Australia) fish

The fatty acid composition of 11 species of fish caught off the northeast coast of Australia was determined. No fatty acid profiles have been previously published for fish from this area nor for nine of these species. Although the percentage of polyunsaturated fatty acid (PUFA) was the same as the calculated average for Australian fish (42.3%), the percentage of n−3 fatty acids was lower (24.4±5.4% vs. 30.7±10.1%) and the n−6 fatty acids higher (16.5±4.5% vs. 11.2±5.9%), P<0.001 in each case. The major n−3 PUFA were docosahexaenoic (15.6 ±6.3%) and eicosapentaenoic acid (4.3±1.1%) while the major n−6 PUFA were arachidonic (8.3±3.2%) and n−6 docosatetraenoic acid (3.1±1.3%). The second-most abundant class of fatty acid was the saturates (31.6±3.5%) while the monounsaturates accounted for 17.4±4.3% of the total fatty acids. The monounsaturate with the highest concentration was octadecenoic acid (11.8±2.6%). There was a positive correlation between the total lipid content and saturated and monounsaturated fatty acids (r=0.675 and 0.567, respectively) and a negative correlation between the total lipid content and PUFA (r=0.774).     

Effects of fructose and troglitazone on phospholipid fatty acid composition in rat skeletal muscle

Skeletal muscle phospholipid fatty acid (PLFA) composition is associated with insulin sensitivity in animal models and in man. However, it is not clear whether changes in insulin sensitivity cause a change in PLFA composition or vice versa. The present studies have examined the effects of agents known to increase or decrease insulin sensitivity on PLFA composition of the major phospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), in soleus and extensor digitorum longus muscle. Four groups of Sprague-Dawley rats— control, 0.2% troglitazone (Tgz), 60% fructose fed, and fructose + Tgz—were treated for 3 wk. Fructose feeding was associated with a decrease in muscle membrane polyunsaturated fatty acids (PUFA) and n-3 fatty acids in both PC and PE. Administration of Igz alone resulted in an increase in liver (3.75±0.93 to 6.93±1.00 μmol/min/mg tissue, P<0.05) and soleus muscle (0.34±0.03 to 0.67±0.09 μmol/min/mg, P<0.01) elongase activity, which would be expected to increase membrane PUFA. However, Tgz decreased PLFA associated with greater insulin sensitivity (e.g., PUFA and n-3 fatty acids) and increased PLFA associated with decreased insulin sensitivity (16∶0 and n-6 fatty acids) in both PC and PE. Co-administration of fructose and Tgz did not reverse the decrease in PUFA observed with fructose alone. We conclude that the improvement in insulin sensitivity reported with Tgz is associated with an apparently paradoxical effect to decrease PUFA and n-3 PLFA composition in rat skeletal muscle. These studies suggest that Tgz-mediated increases in insulin sensitivity do not result in improved PLFA composition.